Integrated circuits are used in a wide range of applications. Integrated circuits are conventionally formed on a wafer of semiconductor material. In order to function properly, the integrated circuit uses various electronic signals that are generated or provided from a source that is external to the integrated circuit, e.g., timing or "clock" signals, and power supply signals.
To connect to these signals, the integrated circuit includes a number of bond pads that are typically formed on the surface of the integrated circuit. The bond pads are coupled to nodes of the integrated circuit that need to receive the specified signals. Further, the bond pads are coupled to the external sources by leads. The leads are connected to the bond pads through bond wires. Conventionally, the bond wires have an arc-like shape that extends outwardly from the surface of the semiconductor substrate. The size, shape and length of these bond wires can hamper the operation of some integrated circuits due to the high resistance and high self inductance of the bond wires.
Mixed mode circuits are one type of circuit that can benefit from low impedance connections between bond pads and leads. A mixed mode circuit is a circuit that includes both an analog circuit and a digital circuit that are formed on the same semiconductor wafer. The mixed mode circuits can benefit from low impedance connections to a ground bus and a guard ring to suppress noise in the analog circuits that is caused by the high speed switching of the digital circuits. Such mixed mode circuits are now being used in microprocessors, memory devices, and other integrated circuits.
High inductance or high impedance connections between bond pads and leads can also introduce noise into the power distribution system of an integrated circuit. For example, high speed synchronous digital circuits require large switching currents. The large switching currents can introduce noise into the power distribution system of the digital circuit when the inductance or impedance of the connections to the power supply and ground busses is too high.
Similarly, circuits that include output drivers with large transient currents also can benefit from low resistance and low inductance connections to various power supply, ground, clock and guard ring busses.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for low impedance, low inductance contacts or connections to power supply, ground, clock, or guard ring buses in integrated circuits.